March 12, 2008

Men, who generally felt most nervous about attractive, rich and strong rivals, were increasingly relaxed, the taller they were themselves. Women, on the other hand, were most jealous of others' beauty and charm, but least so if their own height was average.

This makes evolutionary sense, say the researchers, because previous findings suggest that whilst taller men do best with the ladies, it is women of medium height who enjoy the best health, fertility and popularity with men.

But unlike tall men, medium-height women can be more vulnerable to jealousy under some circumstances. Faced with socially or physically powerful rivals they actually felt more jealous than shorter or taller women. According to the study, this may be because tall and strong, or socially well-connected women could well pose a threat to average-height feminine favourites since they might win conflicts, including physical fights. "Taller women are more dominant and have greater fighting abilities than shorter women," write the researchers in Evolution and Human Behavior

March 11, 2008

In general, scientists agree on how snakes’ venom glands evolved, but that’s not the case for the poisons themselves. Some scientists think that venom is composed of modified proteins from the snakes’ spit that already functioned to break down and digest the prey. Some also believe that the ability to produce poison has evolved independently among the different species of snakes.

But Australian researcher Bryan Fry, one of the world’s leading experts on venomous snakes, has another theory. He has discovered, with the help of DNA analysis, that the vast majority of the proteins and enzymes found in venoms closely resemble substances found in other parts of the snakes’ bodies—substances, for example, that have a function in the liver, or in the digestive organs or some other system. The genes that control the production of these substances in other organs somehow became activated in the salivary glands, where they produce substances that, once modified and refined, are able to help kill the snakes’ prey in an increasingly effective manner.

A common French weed known as Crepis sancta underwent a form of superaccelerated evolution to cope with the difficulties of spreading their seeds in cities. Scientists studying C. sancta discovered that over a period of just twelve years, the plants went from mostly producing dispersing seeds that spread on the wind, to producing nondispersing seeds that fall to the ground nearby. Why would a plant shift its reproductive cycle so radically and quickly?

Seeds that spread on the wind in cities mostly wind up dead on the concrete, while seeds that fall usually find a spot to grow in the same street plots or concrete cracks where their parents grew. You can see the two kinds of seeds at left. Because seeds grew up so close to home, the plants evolved super quickly -- sort of an urban Galapagos Islands effect. One of the ways that Darwin first observed natural selection was on a trip past the tiny, isolated Galapagos Islands, each of which had evolved its own unique types of finches that interbred quickly and in isolation from finches on other islands.

March 01, 2008

Mysteriously, five spacecraft that flew past the Earth have each displayed unexpected anomalies in their motions.

These newfound enigmas join the so-called "Pioneer anomaly" as hints that unexplained forces may appear to act on spacecraft.

A decade ago, after rigorous analyses, anomalies were seen with the identical Pioneer 10 and 11 spacecraft as they hurtled out of the solar system. Both seemed to experience a tiny but unexplained constant acceleration toward the sun.

A host of explanations have been bandied about for the Pioneer anomaly. At times these are rooted in conventional science — perhaps leaks from the spacecraft have affected their trajectories. At times these are rooted in more speculative physics — maybe the law of gravity itself needs to be modified.

Now Jet Propulsion Laboratory astronomer John Anderson and his colleagues — who originally helped uncover the Pioneer anomaly — have discovered that five spacecraft each raced either a tiny bit faster or slower than expected when they flew past the Earth en route to other parts of the solar system.